טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentMeltzman Shai
SubjectChemo-Mechanical Sensing of Gas Phase Substances
DepartmentDepartment of Chemistry
Supervisor Professor Yoav Eichen
Full Thesis textFull thesis text - English Version


Abstract

Over the past three decades, there has been great progress in chemical sensing, as evidenced by the extensive literature on sensing, sensors and artificial chemical senses systems .The first steps in sensing focused on understanding the molecular recognition phenomena and the ways to achieve affinity and selectivity. Yet another related area of intense research centered on the ways to transduce a molecular-level recognition event into a signal that is of relevance to the macroscopic world. Different transduction methods, spanning from optical to electrical and even mechanical means were harnessed to report molecular recognition events. In this research we used silicone microcantilever arrays as mechanical transducers. These tiny beams with typical dimensions of 500 microns (length), 90 microns (width) and 1 micron (thickness) are very sensitive to any surface stress which is formed on top of their surface. Such surface stress is formed when analytes are chemically or physically adsorbed on the microcantilever`s surface. This formation of stress is manifested through the bending of the entire beam which could be monitored using an optical measuring system. This research work had three main targets: 1. during this research we have developed and optimize techniques to selectively etch only the bottom surface of the microcantilevers. In a subsequent step, this surface was coated with a polymer, which served as the chemical sensing layer. 2. Using these techniques of etching and polymer coating we have developed microcantilever based chemical sensors for sensing gas-phase analytes, such as alkylating agents, a chemical group of hazardous materials including warfare agents such as mustards. We studied the interaction between the sensing layer and the analytes and the mechanical properties of the polymer during the adsorption process. 3. We have developed and studied the first (to the best of our knowledge) gas phase enantio-selctive system which is based on microcantilevers. During this research we developed a new approach to polymer coating microcantilevers. Novel chiral polymers served as our chiral sensing layers. We studied the mechanical properties of this polymer as a response to different chiral analytes. In addition, we suggested a mathematical model to describe the enantio-selsctive adsorption process of chiral analytes to the above mentioned novel polymer.